This invention relates generally to automotive lamps. More specifically, the present invention relates to bulb retaining arrangements for releasably retaining a replaceable light bulb assembly in a headlamp.
Modern automotive headlamps are composite assemblies that come in two general types, reflector aimable and housing aimable. In reflector aimable, or movable reflector, construction, only a reflective component is moved with respect to the housing, which remains fixed to the vehicular body. In contrast, the entire lamp unit is pivoted with respect to the vehicular body in housing aimable construction. Nonetheless, both constructions typically include the same primary components, a housing portion having an open end, a light diffusing lens portion affixed to the open front of the housing, and a light bulb. The primary structural difference between the two categories of lamps is the primary reflective element in which the bulb is retained.
In housing aimable headlamps, the housing is the primary reflector and is thus formed with a parabolic reflecting surface and a bulb retaining arrangement located around a center bore at the substantial center of the housing for receiving a light bulb assembly. The retaining arrangement is adapted to maintain the bulb in a predetermined position relative to the socket and the reflecting surface while ensuring a watertight seal around the socket. In reflector aimable headlamps, the housing is not the primary reflector. Instead, an internal reflector, adjustably mounted within the housing, performs that function. Accordingly, the bulb is not retained by the housing but rather by the internal reflector. Thus, in reflector aimable lamps, it is the internal reflector, not the housing, which includes the bulb retention arrangement.
A conventional retention arrangement for a housing aimable headlamp is disclosed in U.S. Pat. No. 5,010,455 to Luallin et al (xe2x80x9cLuallinxe2x80x9d). The arrangement includes three separate arcuate and circumferentially spaced retainer sections surrounding the socket opening. Referring to FIG. 1 of Luallin, each of the retainer sections comprises a pair of axially extending legs integrally formed with the rear of the reflector 12. A bridge member 46 interconnects the legs of each of the retainer sections and has ramp portion 48 formed thereon. In addition, each of the retainer sections is formed with a cutout portion 50 for receiving one of the ears 30, 32, 34 of the light bulb assembly. Also, at least one of the retainer sections has a stop surface. When the ears of the light bulb assembly are inserted into the cutout portions and the light bulb assembly is rotated, the ears initially contact the ramp of each bridge member. This causes the associated bridge member to flex axially outwardly relative to the circular opening. Upon continued rotation of the light bulb assembly one of the ears engages the stop surface after which the bridge member of each of the retainer sections serves to press the light bulb assembly inwardly towards the circular opening to orient the filament of the light bulb axially with respect to the reflecting surface.
Bulb retention arrangements of this type are typically manufactured via injection molding. Injection molding is a common fabrication process in which polymers (xe2x80x9cplasticsxe2x80x9d) are injected into a hollow mold cavity under high pressure. Through this cyclical process identical parts are produced. A typical injection molding cycle consists of the following steps:
melting of plastic resin;
injection of melted plastic resin into the mold;
cooling of the mold; and
ejecting the molded workpiece.
Injection molding offers several advantages in fabrication. Perhaps most significant, injection molding yields a high production rate of substantially uniform parts. Further, the process requires relatively little labor and is thus more economical on average than other production methods.
Retention arrangements of the type disclosed in Luallin provide superior bulb retention and a watertight seal. Further, their integral relation to the rear of the housing allows for economic manufacture via injection molding. However, this type of retention arrangement also has several distinct disadvantages. One significant disadvantage is that the design features of such retention arrangements, characterized by multiple passages and structures lying in differing planes, require relatively complicated tools to manufacture. More importantly, however, is that to form this type of retention arrangement, tool action is necessary. Indeed, additional steps must be performed on each workpiece. First, the housing must be molded. Then, after the mold is opened, a second operation is required wherein a second set of tooling must act on the workpiece to form passages such as those between the rear surface of the reflector and resilient ramp portions. As each step in a manufacturing process increases cost and increases the possibility of error, these multiple steps result in increased costs and decreased quality.
Additionally, the tooling process is further complicated by the fact that a watertight seal is necessary between the lamp and the housing. Thus, additional openings in the housing, which might otherwise simplify the tooling process, cannot be introduced if the necessary watertight seal is to be maintained. Nonetheless, these problems have been tolerated because the retention assembly of this type provides desired bulb retention and a watertight seal. However, in headlamps of the reflector aimable type, where a watertight seal between the lamp and the reflector is not necessary, these disadvantages need to be overcome.
Therefore, it is desirable to provide a bulb retention assembly which provides adequate bulb retention in a headlamp of the reflector movable type. It is further desired that such a retention assembly be designed so as to be injection molded in one step with relatively simple tooling and without tool movement. Finally, it is also desired that such an assembly not be overly complex or expensive to manufacture.
The present invention comprises a reflector for use in a reflector aimable, also known as a movable reflector, vehicle headlamp assembly. The present invention is for use in conjunction with a replaceable light bulb assembly commonly known in the art, with the replaceable light bulb assembly having at least one tab projecting radially outwardly from a socket portion thereof. The present invention comprises a reflector having a front side and a rear side, and a molded body with a bore through the approximate center of the reflector. The bore is suitably positioned and sized for accepting the replaceable light bulb assembly from the rear side of the reflector.
The reflector of the present invention further comprises at least one retainer section integrally molded on the rear side of the reflector and arranged adjacent to the bore. While many embodiments of the present invention are possible and intended to fall within the scope of the claims appended hereto, the exemplary embodiment described herein comprises three retainer sections. Each of the retainer sections comprises a cutout portion, a ramp and a stop feature molded therein. When the replaceable light bulb assembly is inserted into the bore and is rotated, each of the cutout portions of the retainer sections accept the tabs located on the socket portion of the replaceable light bulb assembly. Upon further rotation of the replaceable light bulb assembly, the tabs are then frictionally retained between the ramps and the body of the reflector, with the stop features ensuring that the replaceable light bulb assembly is rotated into proper position.
The reflector of the present invention further comprises mold voids through the reflector which are aligned with the retainer sections. In the exemplary embodiment, three such mold voids are present. The three mold voids are circumferentially spaced around the bore and are generally aligned with the three retention sections. The mold voids are suitably positioned and sized to allow the reflector and the integrally formed retainer sections to be molded in one injection molding step.